The present invention relates to an apparatus for recording, reading, and reproducing radiation image information, and more particularly to an apparatus for recording, reading, and reproducing radiation image information wherein a recording medium composed of a stimulable phosphor layer fixed to an endless support member is circulated for recording a radiation image thereon, the radiation image recorded on the recording medium is photoelectrically read by exposure to stimulating light, and while a recording sheet is being fed in an auxiliary scanning direction by a simple feed means, a light beam modulated by the radiation image thus read or other image information and deflected in a main scanning direction is applied to the recording sheet to reproduce the image as a visible image.
There has recently been developed and widely used, particularly in the medical field, a radiation image recording and reproducing system for producing the radiation-transmitted image of an object using a stimulable phosphor material capable of emitting light upon exposure to stimulating rays When a certain phosphor is exposed to a radiation such as X-rays, .alpha.-rays, .beta.-rays, .gamma.-rays, cathode rays, or ultraviolet rays, the phosphor stores a part of the energy of the radiation. When the phosphor exposed to the radiation is subsequently exposed to stimulating rays such as visible light, the phosphor emits light in proportion to the stored energy of the radiation. The phosphor exhibiting such a property is referred to as a "stimulable phosphor".
In the radiation image recording and reproducing system employing such a stimulable phosphor, the radiation image information of an object such as a human body is stored in a sheet having a layer of stimulable phosphor, and then the stimulable phosphor sheet is scanned with stimulating rays such as a laser beam to cause the stimulable phosphor sheet to emit light representative of the radiation image. The emitted light is then photoelectrically detected to produce an image information signal that is electrically processed for generating image information which is recorded as a visible image on a recording medium such as a photosensitive material or displayed as a visible image on a CRT or the like.
The radiation image recording and reproducing system includes an image reading device for reading the radiation image recorded on a stimulable phosphor sheet. The image reading device reads the radiation image recorded on a stimulable phosphor sheet as follows:
The stimulable phosphor sheet is two-dimensionally scanned by a light beam such as a laser beam, and light emitted from the stimuable phosphor sheet in response to application of the light beam is detected in time series by a light detector such as a photomultiplier or the like, for thereby obtaining image information. The two-dimensional scanning of the stimulable phosphor sheet with the light beam is effected by mechanially feeding, with the light beam is effected by mechanically feeding, sheet in one direction for auxiliary scanning, while deflecting the light beam for main scanning in a direction normal to the direction in which the stimulable phosphor sheet is fed.
The image information thus obtained is sent to an image reproducing device. In the image reproducing device, a recording sheet such as a photographic photosensitive material is exposed to a laser beam modulated by the image information produced from the stimulable phosphor sheet for thereby recording an image on the photographic photosensitive material.
In the radiation image recording and reproducing system, the stimulable phosphor sheet does not serve as a final image information storage medium, but only temporarily stores radiation image information until the radiation image information will be transferred onto and reproduced on the recording sheet as described above. After the stored radiation image information has been read from the stimulable phosphor sheet upon exposure to stimulating light, any radiation energy remaining on the stimulable phosphor sheet is discharged by a method disclosed in Japanese Laid-Open Patent Publication No. 56-11392 or 56-12599 so that undesired remaining radiation image will be erased from the stimulable phosphor sheet. Thereafter, the stimulable phosphor sheet can be used again for recording a radiation image thereon. As a result, the stimulable phosphor sheet is highly economical since it can repeatedly be used in the image reading device.
There has been proposed a radiation image information recording and reading apparatus in which a recording medium composed of a stimulable phosphor layer fixed to an endless support member is circulated for recording a radiation image of an object, the radiation image recorded on the recording medium is photoelectrically read by exposure to stimulating light, and thereafter remaining radiation image information on the recording medium is erased by exposure to erasing light, so that the recording medium can cyclically be reused for recording a radiation image of an object again (see Japanese Laid-Open Patent Publication No. 58-200269).
The endless recording medium is free of the problem of a sheet jam which would otherwise be caused in a sheet feed system by the use of separate sheets such as stimulable phosphor sheets. Another advantage of the proposed apparatus is that the feed system is simple in structure and the overall size of the apparatus is reduced.